Computer will not power on

I have just upgraded my old computer with an additional graphics card (SLI setup) and a new case. Before I upgraded the computer ran just fine. Now when I turn the computer on it runs for only about a second (fans and lights turn on) and then turns off. Everything is plugged in correctly and I have double checked numerous times.  I am almost positive it is a short. I have tested my power supply and am getting power from everything so I don't think it is the PSU. I have tried to insulate all the screw holes on the bother board by putting electrical tape on both sides of the holes to see if the short was being caused from the mother board shorting on the case; however this did not help either. Any suggestions?

ECS elitegroup extreme
Nvidia GeForce 7600 GT X2
Antec true power 2.0 550w
schericAsked:
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mjutrasCommented:
You connected the extra power (if needed) on your videocard? Try only the basic stuff for a display: mobo, videocard,PSU,proc.
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armerdanCommented:
The motherboard needs to be able to ground against the case where the screw holes touch the standoffs for it to work optimaly. You can see a metal ring around the screw holes if you look at the back side (the side where nothing plugs in) those metal rings need to be counded against the chasis.

That won't solve your problem though, it sounds like there are a few possibilities.

1) I would try the PSU from the old case just to see what happens, I asume it was working before.
2) Make sure the CPU fan is spinning, some boards will power down if the fan isn't spimming
3) I know this sounds stupid but when you install the board into the new case you have put standoffs into the case before you screw the board in right, so that all of the solder joints are not grounding out.
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schericAuthor Commented:
The video cards that I am using do not require a power source. I have also removed both cards completely to see if it will even boot up but still no luck.
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schericAuthor Commented:
I currently am still using the old power supply, the only thing i changed out was the extra video cards and new case. I do Believe the CPU fan is spinning, plus i never removed it from the board when changing it into the new case, so there is no way that there were mounting issues. Also I did put standoffs under the board. However i did miss a few holes were  I didn't put any, I actually ran out of extras but i figured it wouldn't be a problem. Could that have anything to do with it?
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armerdanCommented:
As long as there are no solder joints touching the chasis, it should not matter too much that you missed a few standoffs, I don't think that the power supply would just go out on you because you swapped it into a different case.

On the new case does it have a power button or a power switch?
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schericAuthor Commented:
Yeah I don't think the power supply went out either, I even used a power supply tester and I was still getting a power signal. I have a power button connecting directly to the board
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3li0Commented:
Is the PSU adequate enough to sustain an adequate amount of power for both cards? Since the issues seemed to have stemmed from the SLI installation (if you have already tried the following please disregard) why not just pull out the second graphics adapter and see if it will boot normally?

If it does then it is almost certainly that the power being supplied to your setup is somehow not sufficient, or it could indicate a faulty PSU (although Antec for the most part are rather solid PSU's). I've seen quite a number of SLI setups run on 580W and above without any power issues.

You may also want to try an alternate/spare PSU and see if the problem is replicated. You could also dig a little deeper and take a look at your actual OUTPUT, MAX, and MIN loads specs on the PSU and then compute an estimate as to your actual power consumption based on what devices are being used.

Not sure if any of this will really help, but at least they should give you something else to try.
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schericAuthor Commented:
Thanks but I have pulled out one of the cards to see if that was the problems, but it didn't change anything. I also checked the requirements for the 7600GTs SLI set up and they require only 450w.
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3li0Commented:
Well certainly this is certainly interesting. Have you tried any diagnostic testing on any of the other components? Now you mentioned that you used a new case. If there aren't any actual shorts, or any part of the MB exposed to any metal connections as Amerdan has stated, then it's highly possible that something is impeding the signal from the Motherboard power connector, to the case. If that's the case then we may have to take an slightly different approach to this problem.
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schericAuthor Commented:
sorry for the delay had to go to work. What exactly do you mean by impeding the signal? what should I do about this?
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3li0Commented:
Well therein lies the trick, at this point we don't really know at this point too much about the state of the actual Motherboard, there may be something else not allowing power to cycle properly. I would probably check for broken (blown/warped) caps, additionally although unlikely ( I have seen it happen) the actual CMOS can cause power issues, so you may either want to re-seat the actual battery just to make sure. You may need to even try the motherboard in a spare case if necessary - but in general when I have seen failures of this type it indicates a motherboard failure.

I often use the chart located here: http://www.fonerbooks.com/cpu_ram.htm to troubleshoot a number of motherboard, processor, memory and power issues. This may give you some additional ideas. Hope it helps even if a bit ;).
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schericAuthor Commented:
ok so in a scenario were something went bad, is it more likely that the motherboard got damaged? or the CPU? I haven't checked the CMOS yet but I will first before I jump to any conclusions.
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3li0Commented:
That can always be difficult to really assess unless you can physically test the CPU on another motherboard, but at least in my experience most of the time it indicates a Motherboard failure and not necessarily a CPU failure. Also make sure to look at paragraph 5 and 6 on that prior link as it lists some simple tests that can help in determining if the motherboard is actually getting power.
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schericAuthor Commented:
Ok thank you. This helped alot, I think I'll just have to figure it out from here. Thanks for that link btw.
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